Smoking tobacco is the number one risk factor associated with lung cancer. Lung cancer develops when cells in the lungs become damaged and grow uncontrollably, causing tumors that can make it difficult to breathe.

As the tumors grow, the affected cells can also spread to other areas of the body. People who smoke can lower their risk of lung cancer by quitting this habit, which will also improve their respiratory and overall health.

It is important to note that people who do not smoke may still be at risk of developing lung cancer because of environmental and familial risk factors.

In this article, we explore the link between smoking and lung cancer and explain why smoking increases the risk of this disease. We also provide advice on how to decrease the risk and when to seek medical care.

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Years of research have firmly established the link between smoking and lung cancer. According to the Centers for Disease Control and Prevention (CDC), cigarette smoking contributes to about 90% of lung cancer cases in the United States.

Smoking other tobacco products also increases a person’s risk of developing lung cancer. These products include:

  • cigars
  • cigarillos, such as bidis and kreteks
  • loose tobacco that people smoke with a pipe or water pipe

The CDC states that tobacco smoke contains more than 7,000 chemicals, many of which are poisonous. About 70 of the chemicals are known carcinogens, meaning that they can cause cancer.

Inhaling these dangerous substances damages the airways and tiny air sacs, known as alveoli, in the lungs. This damage prevents the lungs from working correctly and increases the risk of the person developing lung cancer and other cancers throughout the body.

The lungs’ primary function is to provide the body with oxygen while expelling unneeded carbon dioxide. Although all tobacco products can cause a person harm, combustible or smoked products, such as cigarettes, are particularly damaging.

Some tobacco products are smokeless, including chewing tobacco and sniffing tobacco, which people may refer to as snuff. Although these products do not produce toxic smoke, they still expose users to more than 25 cancer-causing chemicals.

Research has linked various cancers, including mouth, esophageal, and pancreatic cancer, to smokeless tobacco products. Tobacco use also increases the risk of heart disease and stroke.

Smoking is the leading cause of lung cancer, making a smoker 15–30 times more likely than a nonsmoker to develop or die from lung cancer.

A study in Preventive Medicine Report looked at the risk of smokers developing lung cancer. The researchers found that the average risk for nonsmokers over the study period was 1.8% for males and 1.3% for females. The risk jumped to 14.8% for males and 11.2% for females in current smokers. However, the study did not take into account the number of cigarettes each person smoked per day.

Although smoking increases the chances of lung cancer developing, the disease can also affect nonsmokers. Each year in the U.S., 10–20% of lung cancers happen in people who have either never smoked or smoked fewer than 100 cigarettes in their life.

However, the CDC points out that quitting smoking, regardless of how long a person has smoked, can reduce the chances of dying from lung cancer by half in 10 years.

Lung cancer is the second most common cancer in both males and females. According to the American Cancer Society (ACS), its prevalence is only below that of breast cancer in females and prostate cancer in males.

The ACS estimates that in 2021, there will be about 235,760 new cases of lung cancer and approximately 131,880 deaths from the disease.

Non-small cell lung cancer (NSCLC) is the most common type of lung cancer, accounting for 80–85% of all cases. The remaining 15–20% of lung cancers are small cell lung cancer (SCLC).

The toxic combination of tobacco smoke chemicals damages the lungs’ delicate tissues and causes inflammation.

Alveoli damage

Smoking destroys the alveoli, which allow for oxygen exchange. The destruction is permanent, meaning that this area of the lung cannot recover. Over time, alveoli damage can lead to emphysema, which causes extreme shortness of breath and can prove fatal.

Cilia damage

Healthy lungs are self-cleaning. The chemicals in tobacco harm the fine hair-like cilia that help remove debris from the lungs. Smoking can paralyze and kill these specialized cells, leaving smokers at higher risk of infection.

Airway inflammation

Smoking also causes inflammation of the airways and lungs, leading the person to feel short of breath. If the inflammation continues, it can lead to scar tissue that makes it more difficult for a person to breathe.

Cell behavior

Chemicals in tobacco smoke can damage the DNA that controls how cells behave. For example, the chemical benzo[a]pyrene (BaP) damages a part of the DNA that protects cells against cancer.

These chemicals can also stimulate growth in the damaged cells, which then form a tumor.

Chemicals sticking to DNA

Chromium is a toxic metal present in cigarette smoke. It allows other poisonous chemicals to stick more readily to DNA, increasing the chances of cancer.

Every cigarette someone smokes contributes to lung damage and the likelihood of developing a serious health condition.

People who do not smoke may develop lung cancer due to other risk factors, including:

  • Radon: This gas is the leading cause of lung cancer in nonsmokers. It is responsible for close to 21,000 deaths annually in the U.S., including the deaths of about 2,900 individuals who have never smoked.
  • Secondhand smoke: This is the third leading cause of lung cancer, causing an estimated 3,000 lung cancer deaths every year.
  • Air pollution: Worldwide, polluted air contributes to about 62,000 lung cancer deaths annually.
  • Family history of lung cancer: Having a first-degree relative with a history of lung cancer increases a person’s likelihood of developing the condition by about 50%.
  • Asbestos: Inhaling asbestos fibers increases the risk of lung cancer and mesothelioma, a chest membrane cancer. If an individual smokes, this further increases their risk of these conditions.

Researchers believe that avoiding modifiable risk factors could prevent up to 50% of cancer cases and as many as 90% of lung cancer deaths.

A person can reduce their risk of lung cancer by:

  • eating a nutritious diet
  • drinking alcohol only in moderation
  • maintaining a moderate weight
  • quitting smoking, if a smoker, or avoiding secondhand smoke

People who smoke can reduce their risk of lung cancer by making every effort to stop. Quitting smoking can be challenging, but a person may benefit from adopting the following measures:

  • Thinking positively: Having a positive mindset is essential, even if an individual has found previous attempts to quit smoking too difficult.
  • Learning about triggers: Understanding what triggers the need to smoke may help people deal with their cravings more effectively.
  • Making a plan: Choosing a future date to stop smoking and sticking to the decision can help a person focus and stay motivated.
  • Concentrating on the reasons: It may help a person to think about the dangers of smoking and to focus on how quitting may improve their health and save them money.
  • Seeking medical advice: A person can ask a doctor for advice about quitting smoking. The doctor might recommend medication to help with nicotine withdrawal. Nicotine patches and other forms of nicotine replacement therapy, such as chewing gum or lozenges, can increase the likelihood of success.
  • Getting support: In-person, telephone, text, or virtual counseling can help a person through the stressful process of quitting and increase their likelihood of becoming smoke-free.
  • Telling family and friends: When an individual has the support of their family and friends, it can make quitting smoking easier. Sharing the plan to quit can also help by making the person feel accountable.

Get more tips on how to give up smoking.

A person should contact a doctor if they are experiencing any symptoms of lung cancer, including:

There are other possible causes of these symptoms, so they do not necessarily indicate lung cancer. However, seeking medical advice is a wise precaution to rule out any severe health conditions.

Smoking is a significant risk factor for lung cancer. People who smoke may be up to 30 times more likely to develop this cancer than nonsmokers.

Environmental factors and a family history of lung cancer can also make the disease more likely.

It is never too late to quit smoking. Stopping smoking can reduce a person’s risk of lung cancer by half after 10 years.

A person should speak with a doctor if they are experiencing lung cancer symptoms or believe that they have a high risk of developing the condition.